After losing his mother, Itou Katsuya found himself under the care of his guardian, Tooru. But Katsuya struggled with the memories of his mother's death, unable to recall the details. Compounding his distress were the confusing emotions he felt towards Tooru, feelings that went beyond those of a typical son towards his father figure. As Katsuya navigated puberty, life with Tooru became unbearable.
One day, Katsuya crossed paths with a man who claimed to be a friend of his mother's. This man revealed that Katsuya's mother had been the victim of a hit-and-run accident, one that remained unsolved to this day. Determined to uncover the truth about his mother's death, Katsuya sets out on a quest to find her killer. But the journey is made all the more difficult by the taboo feelings he harbours for Tooru.
